1. Class: Crustacea
Order: Phyllopoda
Suborder: Cladocera
Family: Chydoridae
Alona rectangula Sars
Description:
Plate 022a. Lateral view of Alona rectangula, with postabdomen extended.
Plate 022b. Rostrum and antennule of Alona rectangula.
Plate 022c. Postabdomen of Alona rectangula, marginal fasicles extend
beyond its margin.
Plate 022d. Valve of carapace of Alona rectangula showing striation and
ventral spines
A common species, Alona rectangula is a component of the pelagic plankton, but
usually not in great numbers. Its valves may be striated, reticulated, or smooth. The
postabdomen short, slightly enlarged toward apex, angle rounded, with 8-9 marginal
denticles or setae. Fasicles (an inner margin of small spines) line the postabdomen,
the distal of these extend beyond the margin of the abdomen. The antennule does
not extend beyond the rostrum. .

2. Plate 022a. Lateral view of Alona rectangula, with postabdomen extended.

3. Plate 022b. Rostrum and antennule of Alona rectangula.

4. fasicles
denticles
Plate 022c. Postabdomen of Alona rectangula, marginal denticles and
fasicles (an identifiable character) extend beyond its margin.

5. Plate 022d. Valve of carapace of Alona rectangula showing striation and
ventral spines.